lte l11 radio network functionalities

NASlide title In CAPITALS 44 pt Slide subtitle 20 pt
L11A Radio Network Functionalities
Slide title In CAPITALS 44 pt Slide subtitle 20 pt
Introduction
© Ericsson AB 2009 | Ericsson Internal | X (X) | Date
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Your job in the introduction is to motivate the student for learning this module and give some planning information like what the student will be able to do after taking the module and what the content of the module will be. Furthermore learning is enhanced if first giving an overview presentation of the topics.
There are 3 main blocks of your presentation. This is the Introduction in the Prepare for learning block.
Prepare for learning
Summary
Why learn about L11A Radio Network Functionalities
LTE
LTE
LTE
RRC
LTE
SON
ANR
This module will help you understand features and functions supported by Ericsson L11A product.
Also you will understand which licencies are needed in order to provide high data rates.
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Scope and objectives
Explain Optional features related to Radio Network
Objectives
Scope
Upon completion of this course, the student will be able to:
List basic and optional features in L10A
Explain basic Radio Network Features such as:
Idle Mode Support,
System Information Broadcast
Explain basic Transport Network Interfaces
S1 Protocol Model
Explain Optional features related to Radio Network such as
Dual anntenna DL Performance
WCDMA Session Continuity – Coverage Triggered
GRAN Session Continuity – Coverage Triggered
Explain Optional Transport Network Features
Support for X2 Interface
> Overview
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Start by giving a 30-60s overview of the module. This will significantly help the learners to understand the rest of the module.
Try to include:
Defining the setting. What are we talking about, e.g. Broadband market is evolving giving operators new opportunities.
Who should care about this? E.g. You (the KAM) need to act on this, because it gives you new opportunities.
What have happened? E.g. Consumer behaviours/new technology/standards have made XXX a profitable opportunity for operators.
Where do they wan’t to be? E.g. You wan’t to be the one guiding the operators to reap the benefits of these possibilities.
What do they need to do? E.g You need to tell the operators A, B, C...
RAN Functionality Products
Clock Source over NTP
CDMA2000
Support for cascading of 3GPP Compatible RET Antennas
Support for 3GPP Compatible TMA
Support for 3GPP Compatible RET
Antennas
RAN Functionality Products are divided into LTE Basic Functions and LTE Optional Functions
Optional Functions are divided into 7 areas:
Radio Performance
Product is scalable on a number of Connected Users.
Please Note: Grey boxes are related to L10 release of the product
And green are related to L11A. This is only an overview figure.
Lte basic features
The Main topic is included in the Learning part of the module where you present the topics to learn.
Think of this when sequencing the included topics:
Is there a logical order to present? Chronology, process, cause->consequence
Start with the simple and build to complex.
Start with the well known (or analogies) and move to the unknown.
Do not include everything you have to say. Remember that most learning content is forgotten within a couple of days.
Focus on a few key concepts where you don’t want your audience to do the wrong thing in their work. Let the details remain on the intranet, guidelines, documentation etc.
LTE Basic Features
LTE Basic - Radio
LTE Basic is a software package that performs all operations needed for an LTE Radio Access Network (RAN). It is a large group of functions assembled into one working system with basic performance.
LTE Basic can be divided into three main areas:
LTE Basic Radio
Lets´ look at each one of them.
LTE Basic Features
IDLE MODE SUPPORT
MME
SGW/
PGW
LTE Basic Package for Radio includes
Idle Mode Support that includes all the functions needed by the UE to access the radio network such as System Information Broadcast and Paging.
For the UEs in the Connected mode there are functions in the eNB to support scheduling of the services, power control and link adaptation.
LTE Basic provides Single Data Radio Bearer Service per user supporting end user with single non Guaranteed bit rate service that can be used for carrying best effort type of traffic.
Also included in the basic package is traffic security for radio interface based on integrity protection and ciphering of the RRC messages as well as ciphering of the user plane data. In L10 there is only support for Integrity protection and Ciphering is been added in L11
idle mode support
IDLE MODE SUPPORT
Idle mode support feature provides mechanism to support broadcast of the system information
And paging messages from the Network side.
UE in idle mode is responsible for monitoring System Information Change by monitoring Paging. Performing PLMN and Cell reselection.
UE is also responsible to perform location registration.
IDLE MODE SUPPORT:
PLMN Selection
Location Registration
The idle mode tasks can be subdivided into four processes:
- PLMN selection;
.
The UE registers its presence, by means of a NAS registration procedure, in the tracking area of the chosen cell.
As outcome of a successful Location Registration the selected PLMN becomes the registered PLMN.
If the UE finds a more suitable cell, according to the cell reselection criteria, it reselects onto that cell and camps on it.
If the new cell does not belong to at least tracking area to which the UE is registered, location registration is performed.
If necessary, the UE shall search for higher priority PLMNs at regular time intervals and search for a suitable cell if another PLMN has been selected by NAS.
Search of available CSG IDs may be triggered by NAS to support manual CSG ID selection within the registered PLMN.
If the UE loses coverage of the registered PLMN, either a new PLMN is selected automatically (automatic mode), or an indication of which PLMNs are available is given to the user, so that a manual selection can be made (manual mode).
The purpose of camping on a cell in idle mode is following:
a) It enables the UE to receive system information from the PLMN.
b) When registered and if the UE wishes to establish an RRC connection, it can do this by initially accessing the network on the control channel of the cell on which it is camped.
c) If the PLMN receives a call for the registered UE, it knows (in most cases) the set of tracking areas in which the UE is camped. It can then send a "paging" message for the UE on the control channels of all the cells in this set of tracking areas. The UE will then receive the paging message because it is tuned to the control channel of a cell in one of the registered tracking areas and the UE can respond on that control channel.
d) It enables the UE to receive ETWS notifications.
If the UE is unable to find a suitable cell to camp on, or the USIM is not inserted, or if the location registration failed it attempts to camp on a cell irrespective of the PLMN identity, and enters a "limited service" state in which it can only attempt to make emergency calls.
IDLE MODE SUPPORT:
Cell Search Procedure
PSS
SSS
Detection of cell id group (0-167)=> PCI
Detection of MIMO & CP configuration
Possible to read Sys Info
& RS (timing, seq, freq shift)
The cell search procedure allows the UE to acquire the slot and frame synchronization and to get the downlink cell ID and cell ID group associated with the cell. The physical signals involved in the cell search procedure are the Primary and Secondary Synchronization Signal (P-SS and S-SS). The procedure is based on the following steps:
Detection of the carrier frequecy
Detection of the symbol timing
Identification of the cell id – one out of 3 possible
Once cell id is detected next step is to
Detect radio frame timing
Detect Physical Cell Id (PCI) one out of 168
When the terminal has determined the cell ID, frame timing and CP length, it has to determine the number of transmit antennas used for PBCH.
That also has to be blindly detected by the UE.
IDLE MODE Support:
Cell Selection (S-Criterion)
*Pcompensation = max(pMaxServingCell – P;0)
S>0
The cell selection criterion (the S criterion) is based on the measured Reference Signal Received Power (RSRP) level in the cell, normalized with respect to the minimum required receive signal level in the cell and certain compensations.
The cell selection criterion is fulfilled if:
S rxlev > 0
S rxlev = Q rxlevmeas - (Q rxlevmin + Q rxlevminoffset) - P compensation
The UE obtains the S rxlev value using the following measurements and parameter values:
Q rxlevmeas Measured RSRP value in the cell (dBm) Q rxlevmin Required minimum RSRP level in the cell (dBm) Q rxlevminoffset Offset to Q rxlevmin taken into account in the S rxlev evaluation as a result of a periodic search for a higher priority PLMN (not provided in the current release of the LTE Basic). Default value: 0 (dBm) P compensation Compensation [max (P EMAX - P UMAX, 0)] if the maximum power according to the UE capability (P UMAX) is less than the maximum UE power to be used in the cell (P EMAX). For further information, see the document 3GPP TS 36.304 .
The configuration parameters to set the cell selection criteria in the cell are:
qRxLevMin Required minimum RSRP level in the E-UTRA cell. Corresponds to parameter Q rxlevmin in the document 3GPP TS 36.304 .
pMaxServingCell Maximum UE power to be used in the cell. If absent, the UE applies the maximum power according to UE capability. Corresponds to parameter P EMAX in the document 3GPP TS 36.101 .
Idle Mode Support:
Once UE has performed cell selection than it is in the state “Camp Normally”.
State Camp Normaly means that the UE will:
Monitor System Information
Idle mode support:
The system information is a set of parameters that defines rules for the UE how to behave while visiting the cell.
The UE shall apply the system information acquisition procedure:
upon selecting (e.g. upon power on) and upon re-selecting a cell,
after handover completion,
upon receiving a notification that the system information has changed,
upon receiving an indication about the presence of an ETWS notification and
upon exceeding the maximum validity duration
System information is divided into the Master Information Block (MIB) and a number of System Information Blocks (SIBs). The MIB includes a limited number of most essential and most frequently transmitted parameters that are needed to acquire other information from the cell, and is transmitted on BCH.
SIBs other than System Information Block Type 1 are carried in System Information (SI) messages and mapping of SIBs to SI messages is flexibly configurable by scheduling Info List included in System Information Block Type1.
MIB is sent on the PBCH while SIBs are sent on PDSCH. PDCCH will indicate that System Information is been transmitted using SI-RNTI identity.
There is only one SI-RNTI per cell.
In L11A there is support for SIB4, SIB5, SIB6 SIB7 and SIB8
LTE BASIC: IDLE MODE SUPPORT
Cell Reselection (R-Criteria)
The Cell Reselection process is run when:
When the cell on which it is camping is no longer suitable.
When the UE, in ”camped normally” state, has found a better neighboring cell than the cell on which it is camping.
When the UE is in limited service state on an acceptable cell.
When camped on an E-UTRA cell, the UE performs a ranking of neighboring E-UTRA cells on the same frequency, taking into account the cells satisfying the cell selection criteria.The cell ranking is based on the RSRP measurement quantities of the serving cell (Q meas,s) and the neighboring cells (Q meas,n).
The UE applies the cell ranking criterion R s on the serving cell, and the cell ranking criterion R n on the intra-frequency cells:
R s = Q meas,s + Q hyst R n = Q meas,n
Q hyst is a hysteresis value preventing too-frequent reselection back and forth between cells of nearly equal rank. When a neighboring cell is ranked as better than the serving cell (that is, R n > R s) during a time interval T reselectionEUTRA, the UE performs a cell reselection to the better-ranked cell.
The configuration parameters to set intra-frequency cell reselection in the cell are :
qHyst Cell reselection parameter that defines the hysteresis value in the intra-frequency cell ranking criteria. Corresponds to parameter Q hyst in the document 3GPP TS 36.304 .
tReselectionEutra Cell reselection timer value for an E-UTRA frequency. Corresponds to parameter T reselectionEUTRA in the document 3GPP TS 36.304 . qRxLevMin ( neighboring cells ) Required RSRP level in the intra-frequency neighboring cells. Corresponds to parameter Q rxlevmin in the document 3GPP TS 36.304 . pMax Maximum UE power to be used in neighboring cells on the E-UTRA frequency. If absent, the UE applies the maximum UE power for the UE power class. Corresponds to parameter P EMAX in the document 3GPP TS 36.101.
Idle mode support:
Three mobility states: Normal, Medium and High
Based on the no of cell reselections made by the UU
Normal
Qmeas(n)
Qmeas(s)
R(s)
R(n)
tReselectionEutra
The speed-dependent scaling of cell reselection criteria is used to influence the cell reselection criteria for fast moving UE. It helps the UE to respond more quickly to cell changes when moving at high speed. A UE may enter three different mobility states:
Normal
Medium
High mobility
The usual T reselectionEUTRA and Q hyst parameters are used in the normal mobility state for the evaluation of cell reselection criteria
In the medium and high mobility states, the UE applies a scaling factor, decreasing the value of the T reselectionEUTRA parameter. In that way, the evaluation period of cell reselection criteria is reduced.
In addition, a negative offset is added to the Q hyst hysteresis value in the cell ranking criteria. It lowers the threshold for the reselection of intra-frequency cells.
The criteria for the UE to enter the medium and high mobility states are based on the number of recent cell reselections performed by the UE. A sliding time window is used. The parameter T CRmax determines the duration of the sliding time window.
The parameters N CR_M (medium mobility) and N CR_H (high mobility) determine the number of cell reselections the UE performs within the sliding time window to enter the medium and high mobility states. The UE applies an additional time period before reentering the normal mobility state.
Once in the medium or high mobility state, the UE re-enters the normal mobility state when the number of cell reselections during the sliding time window (T CRmax) stays below the parameter N CR_M and N CR_H values during a period equal to the additional time period.
The parameter T CRmaxHyst determines the duration of the additional time period.
The configuration parameters to set speed-dependent scaling of cell reselection criteria are specified in 3GPP TS 36.304 and described in the following tables:
tEvaluation Duration for the evaluation of the entering criteria to the mobility states. Corresponds to 3GPP parameter T CRmax. tHystNormal Additional duration for the evaluation of the reentering criteria to the normal mobility state. Corresponds to 3GPP parameter T CRmaxHyst.
nCellChangeMedium Number of cell changes to enter the medium mobility state. Corresponds to 3GPP parameter N CR_M.
nCellChangeHigh Number of cell changes to enter the high mobility state. Corresponds to 3GPP parameter N CR_H.
qHystSfMedium Reduction of the Q hyst parameter applied in medium mobility state. Corresponds to 3GPP parameter sf-Medium of Speed dependent ScalingFactor for Q hyst.
qHystSfHigh Reduction of the Q hyst parameter applied in high mobility state. Corresponds to 3GPP parameter sf-High of Speed dependent ScalingFactor for Q hyst. tReselectionEutraSfMedium Scaling of the T reselectionEUTRA parameter in medium mobility state. Corresponds to 3GPP parameter sf-Medium of Speed dependent ScalingFactor for T reselectionEUTRA. tReselectionEutraSfHigh Scaling of the T reselectionEUTRA parameter in high mobility state. Corresponds to 3GPP parameter sf-High of Speed dependent ScalingFactor for T reselectionEUTRA.
IDLE mode Support:
There are two types of paging!
The first one is Core Network initiated paging as a resoult of incoming data/incoming session.
The other one is eNodeB initiated paging that can be trigered when System Information has been changed.
In first scenario paging is only relevant for one UE while in second one paging targets all UEs in the cell.
IDLE mode support:
DRX Paging Frame
PFindex when: SFN mod T= (T div N)*(UE_ID mod N)
i_s = floor(UE_ID/N) mod Ns
nB: 4T, 2T, T, 1/2T, 1/4T, 1/8T, 1/16T, 1/32T
N: min(T,nB)
Ns: max(1,nB/T)
PF : SFN mod T=
0, 64, 128…
The UE may use Discontinuous Reception (DRX) in idle mode in order to reduce power consumption.
One Paging Occasion (PO) is a sub frame where there may be P-RNTI transmitted on PDCCH addressing the paging message. One Paging Frame (PF) is one Radio Frame, which may contain one or multiple Paging Occasion(s). When DRX is used the UE needs only to monitor one PO per DRX cycle.
PF and PO is determined by following formula using the DRX parameters provided in System Information:
PF is given by following equation:
SFN mod T= (T div N)*(UE_ID mod N)
Index i_s pointing to PO from sub frame pattern defined in the table will be derived from following calculation:
i_s = floor(UE_ID/N) mod Ns
System Information DRX parameters stored in the UE shall be updated locally in the UE whenever the DRX parameter values are changed in SI. If the UE has no IMSI, for instance when making an emergency call without USIM, the UE shall use as default identity UE_ID = 0 in the PF and i_s formulas above.
The following Parameters are used for the calculation of the PF and i_s:
-T: DRX cycle of the UE. T is determined by the shortest of the UE specific DRX value, if allocated by upper layers, and a default DRX value broadcast in system information. If UE specific DRX is not configured by upper layers, the default value is applied.
-nB: 4T, 2T, T, T/2, T/4, T/8, T/16, T/32.
-N: min(T,nB)
-Ns: max(1,nB/T)
-UE_ID: IMSI mod 1024.
IMSI is given as sequence of digits of type Integer (0..9), IMSI shall in the formulae above be interpreted as a decimal integer number, where the first digit given in the sequence represents the highest order digit.
Idle mode support:
Normal registration
Periodic registration
A TA is the set of E-UTRA cells in a PLMN, identified by a common Tracking Area Code (TAC) in the system information. When a UE registers itself in the network, the core network stores information about the tracking area where the registration is performed. This information is used, for example, to assist the UE paging.
The tracking area update procedure is used by the UE to update the registration of its actual tracking in the network. The core network provides the UE with a list of tracking areas where the registration is valid. The UE performs a new registration, either after a certain time (periodic registration), or when it enters a new tracking area where the registration is no longer valid. The operator configures the TAC associated with each cell.
SINGLE DATA RADIO BEARER PER USER
LTE
MME
SGW
PGW
PCRF
WWW
The Radio Bearer Service feature provides the service of establishment and release of signaling and data radio bearers.
LTE Basic functions offer a single data radio bearer per user. The bearer provides the basic path for carrying user data packets. The signaling radio bearers come with the single data radio bearer, providing the possibility to send Access Stratum (AS) and Non-Access Stratum (NAS) messages between the User Equipment (UE) and the network.
The radio bearer contains underlying parameters that influence bit rate and delay, as well as radio bearer coverage and capacity. These parameters are not connected directly to this feature. They are configured through other features, such as Quality of Service (QoS). The single data radio bearer per user service supports a single non-guaranteed bit rate service data flow used for carrying best effort type of traffic.
Radio Bearer Carries data over the Uu air interface. Types of radio bearers include:
Data radio bearer for the user plane
Signaling radio bearer for the control plane
LTE RAN can support up to eight data radio bearers and two signaling radio bearers for each UE. In order to support more than one DRB (1) the feature Multiple Radio Bearers per User must be activated. Two SRBs (2) are defined by 3GPP. SRB1 is used for normal RRC (3) signaling between the RBS and the UE. SRB2 is used only to carry NAS signaling and has lower priority than SRB1. EPS Bearer Carries user plane data between the UE and the PDN-GW. Each EPS bearer is mapped to a data radio bearer, an S1 bearer, and an S5/S8 bearer. E-RAB (4) The data radio bearer and the S1 bearer together are some times addressed as E-RAB). It carries user plane data between the UE and the SGW (5). E-RAB is the name used in 3GPP S1AP specifications. A one-to-one mapping always exists between an E-RAB and a DRB. S1 Bearer Carries user plane data between the RBS and the SGW. S5/S8 Bearer Carries user plane data between the SGW and the PDN (6) gateway.
LTE BASIC:
Scheduler
Scheduling, Link Adaptation and UL Power Control are three essential functions in the eNB. They interact closely and exchange information in order to be able to allocate an appropriate amount of resources, with the right transport format, modulation and coding as well as appropriate UL power at every TTI. The QoS framework also influences the prioritization of logical channels
QoS Framework provides mechanisms to translate CN QoS parameter Quality of Service Class Indicator (QCI) into RAN parameters.
QCI is a scalar that is used as a reference to access node specific parameters that control bearer level packet treatment (e.g. scheduling weights, admission thresholds, queue management thresholds, link layer protocol configurations etc).
Scheduling is also referred to as Dynamic Resource Allocation (DRA) and is part of the Radio Resource Management (RRM). There are important interactions with other RRM functions such as power control, link adaptation and Inter-cell Interference Control
In order to provide efficient resource usage the LTE concept supports fast scheduling where resources on the shared channels PDSCH and PUSCH are assigned to users and radio bearers on sub-frame basis according to the users momentary traffic demand, QoS requirements and estimated channel quality. This task is done by the uplink (UL) and downlink (DL) schedulers, both situated in the eNB.
In the downlink, the resources handled by the scheduler per cell are:
Physical Resource Blocks
DL Power
PDCCH Resources
TX rank
In the uplink , the resources handled by the scheduler per cell are:
Physical Resource Blocks
PUCCH Resources
Common resource is the baseband processing power of the RBS. There are different licenses for UL and DL UlBasebandCapacity DlBasebandCapacity (Mbps)
Link Adaptation, which includes transport format selection, is closely related to scheduling and the two functions interact by exchanging information prior to each scheduling decision.
Link adaptation adapts MCS (code rate, QPSK, 16-QAM, 64-QAM). Adaptation is based on link quality estimation (CQI)
Used for new transmissions and retransmissions
HARQ OPP used as DL quality requirement. HARQ OPP is targeted no of tx and resulting BLER. BLER is used for channels without HARQ
SINR used for UL LA
Worst case LA used for initial messages (PBCH, BCCH, PCH and RA response). This means MCS is chosen to reach cell edge
Antenna mapping, also part of Link Adaptation, controls multi-antenna transmission by deciding the antenna mapping mode (TX diversity, spatial multiplexing or beam forming, as well as sub modes within each mode), spatial multiplexing rank and spatial multiplexing precoding matrix.
Channel prediction provides information needed for decisions in the other Link Adaptation functions and Power Control. It includes collecting channel measurements, made in the downlink by the UE and sent to the RBS in channel feedback reports containing CQI, precoding matrix indicator (PMI), and rank indicator (RI). In UL the SINR is considered.
Power control and power configuration reduces inter-cell interference and power consumption. This leads to higher cell capacity and the control of maximum data rate for a UE at cell edge. In addition, it maximizes battery life for the UE.
Power Control is used to minimize the transmitted power and to compensate for channel fading. Its objective is to maximize capacity by minimizing power and interference.
Power control regulates the PSD (Power Spectral Density) of the transmitted signal.
open loop Power Control
Regulating power for PRACH at initial access (Random Access)
Regulating power for PUSCH and PUCCH as part of UL power control
UL power control
Uplink power control is used both on the PUSCH and on the PUCCH. In both cases, a parameterized open loop combined with a closed loop mechanism is used. Roughly, the open loop part is used to set a point of operation, around which the closed loop component operates. Different parameters (targets and 'partial compensation factors') for user and control plane are used
L11 improvements
Power Control for PUSCH and PUCCH Maintains PSDRX at the RBS and Controls UE’s PSDTX.
As already mentioned Power Control can be divided into two components:
Open loop
Compensates estimation errors of Open Loop
In release L10B, PUSCH power control relied on the OL power control using a hard coded p0-NominalPUSCH. For CL power control, the eNodeB always issued TPC commands requesting 0 dB change.
In release L11A, the eNodeB will check received PUSCH power for each PUSCH transmission and when needed send a TPC command requesting the UE to increase or decrease its transmission power. Both OL and CL power control use the same p0-NominalPUSCH and this is operator configurable using the EUtranCellFDD.pZeroNominalPusch MOM attribute. The same concept of OL and CL power control exist not only for PUSCH, but also for the PUCCH. For PUCCH, release L10B already had full support for both OL and an active CL control, but in release L10B the p0-NominalPUCCH was hardcoded. Release L11A makes p0-NominalPUCCH operator configurable using the EUtranCellFDD.pZeroNominalPucch MOM attribute.
HARQ Retransmissions:
Support for HARQ Retransmissions is a part of LTE Basic. Release L11A introduces this feature.
HARQ combines Forward Error Correction Coding (FEC) and error detection using Transport Block (TB) checksum to achieve incremental redundancy transmission.
The basic concept of HARQ is that the transmitting part takes a TB, in LTE a MAC level PDU, adds a checksum for error detection, performs FEC, and then in a first transmission only sends the MAC PDU, the TB checksum, and a minor part of the redundancy information calculated by the FEC.
If the receiving part after FEC decoding detects that checksum of decoded data is incorrect, it issues a Negative Acknowledgement (NACK) for the HARQ. When the transmitting part receives this NACK, in its next transmission attempt it sends more of the redundancy information, called next Redundancy Version (RV). The receiving part can then combine first received data with the new retransmission and make a new attempt to decode the data.
Should detection still fail after a number of transmission attempts, a HARQ failure is declared and transmitter proceeds with the next TB (MAC PDU). In these cases, the content of the failed MAC PDU must be retransmitted by higher layers, that is, RLC.
In release L10B, the eNodeB does not support retransmissions using HARQ, neither for uplink or downlink. Instead the system relied completely on the retransmissions provided by the RLC layer using Acknowledged Mode (AM), which is used both for Signalling Radio Bearers (SRBs) and Data Radio Bearers (DRBs). (In release L11A RLC AM is used for SRB and PRB.)
Note:
In release L11A, RLC AM is used for SRB and all DRBs. Release L10B implementation is the following:
For downlink, the eNodeB is in full control and for every TTI, it informs the UE whether transmission is a first transmission or a HARQ retransmission. Retransmissions were never issued in release L10B.
For uplink, the eNodeB, using RRC signalling, informed the UE that the maximum allowed number of HARQ transmission was one, which prevented the UE from attempting any asynchronous HARQ retransmissions (asynchronous retransmissions are retransmissions not explicitly granted by the eNodeB). As an extra protection against undesired asynchronous HARQ retransmission from UE, the eNodeB on Physical Hybrid Automatic Repeat Request Indicator Channel (PHICH) issued a positive acknowledgement (HARQ ACK) for every granted uplink transmission, regardless of whether reception is successful, checksum incorrect, or even no UE transmission detected.
To reduce the amount of RLC retransmissions in release L10B, the link adaptation algorithms of the eNodeB had an operating point (target value) of about 1% block errors on MAC level, that is, 1% of received MAC PDUs can have an incorrect checksum. When a MAC PDU is lost corresponding RLC PDUs are also lost, and when the receiver detects that the PDU has been lost, it requests a retransmission on RLC layer.
Release L11A introduces HARQ with a maximum of four transmission attempts (a first plus up to three retransmissions), both for uplink and downlink data transfer. The retransmissions are stopped when the receiving part issues a positive HARQ ACK, or when the total number of transmissions has reached four.
For downlink transmissions, UE sends HARQ ACK/NACK on PUCCH or PUSCH; the latter if UE has a PUSCH allocation in the TTI where HARQ ACK/NACK is to be sent).
For uplink transmissions, the eNodeB sends HARQ ACK/NACK on PHICH.
HARQ retransmissions significantly improve capability of the MAC layer to cope with bit errors on the air interface. For that reason, link adaptation is more aggressive selecting higher MCS or TBS, or both, resulting in higher throughputs in medium to poor radio conditions. For release L11A, the target Block Error Rate (BLER) used by link adaptation is about 10% for one transmission.
L11 Improvements
UE Category Handling:
In L11A eNodeB dynamically adapts its scheduling to what UE has reported regarding its category, both concerning UL and DL scheduling.
However until eNobeB has received the “UECapabilityInformation”, all scheduling decisions assume lowest ue-category.
In LTE there are 5 different categories. For more information what those different category includes in terms of supported modulation, no of layers, size of the soft buffers etc can be found in TS 36.331
In L10B it is assumed that all UEs have same category – cat3.
L11 Improvements:
No SR over PUCCH but periodic UL Grant
Periodic CQI reports over PUCCH every 40 ms
SR over PUCCH every 10 ms
L10B
L11A
SR and CQI Reporting over PUCCH
SR and CQI Reporting over PUCCH is a part of LTE Basic. Release L11A introduces this feature.
The PUCCH carries uplink control information from user equipment for which no PUSCH resource is assigned. For UE already assigned a PUSCH in a TTI, the control signalling is multiplexed with data onto PUSCH.
PUCCH is used by UE for transmitting the following:
ACK/NACK for HARQ
SR used by UE for requesting grant for uplink transmission on PUSCH
Periodic reporting of Channel Quality Indicator (CQI)On the same resources, UE also reports Rank Indicator (RI).
LTE release L10B only used PUCCH for UE reporting of ACK/NACK on downlink transmissions (HARQ ACK/NACK), and eNodeB used this for link adaptation. All CQI/RI reporting was done over PUSCH using eNodeB requested aperiodic CQI reports. Release L10B did not use SR over PUCCH and instead all UE in RRC_CONNECTED state were periodically given an uplink grant.
LTE release L11A introduces PUCCH also for SR and periodic channel status reporting (often called CQI reporting, but which also includes reporting of RI).
In release L11A, implementation of this feature is mandatory and all UE in RRC_CONNECTED state must be assigned its own dedicated resource for SR over PUCCH (every 10 ms) and its own resource for periodic CQI/RI reporting over PUCCH (every 40 ms). When PUCCH resources for a cell has been exhausted, no new UE connections will be accepted until the resources have been returned by UE leaving RRC_CONNECTED state in the cell.
In release L11A, the eNodeB for each cell supports the following:
One PRB pair for PUCCH format 2 (CQI/RI reporting)
Up to two PRB pairs for PUCCH format 1 (SR and HARQ ACK/NACK)
Three PUCCH PRB pairs consume four PRBs of the configured uplink cell bandwidth, for example for 20 MHz = 100 PRBs, 96 PRBs remain for PUSCH allocations.
LTE Basic Features
LTE Basic provides a Transport Network that supports robust connectivity between eNodeB, OSS-RC and EPC. Standard compliant interface termination is supported. Basic quality of service is also provided to allow the operator control the performance of the different services on the upper layers.
LTE Basic provides termination of the S1 and Mul (eNodeB<- >OSS-RC)
interfaces, QoS handling, Network Synchronization using GPS and Transport
Network Observability.
S1 Interface Termination
The two S1 interfaces are S1-MME (towards an MME) and S1-U (towards an
SAE GW). There may be multiple S1-MME and multiple S1-U logical interfaces
towards the EPC from any one eNodeB
Mul Interface Termination
The Mul interface is based on IPv4. See B1.4.8 for details on OAM related
functionality.
Quality of Service Handling
QoS is managed by mapping of the QCI (radio bearers) to DSCP (IP layer) to
pBits (Ethernet layer). The mapping between QCI and DSCP is configurable
by the operator in OSS-RC.
Transport Network Performance Indicators
Monitoring of S1 control plane link availability, packet loss in the network, data
volume and general IP/Ethernet monitoring is supported as part of LTE Basic.
These are important transport network performance measures which can be
used to check compliance to Service Level Agreements.
Network Synchronization using GPS
an external clock source based on GPS PPS protocol.
This allows network synchronization to be independent from the performance
of the network.
In L11A this basic feature has been improved with time and phase synchronization
using GPS. The result is that SFN (System Frame Number) initialization time for radio frame transmission is correlated to an external source.
The purpose with this L11 improvement is coexistence with CDMA2000. Having this feature eNB can provide system time information of the cdma200 for the mobility purposes.
LTE BASIC:
S1 Interface
procedures between the EPC and E-UTRAN
conveying messages transparently between the EPC and the UE without interpretation or processing by the E-UTRAN.
Facilitate a set of general E-UTRAN procedures from the EPC such as paging-notification as defined by the notification SAP.
Separate each User Equipment (UE) on the protocol level for mobile specific signalling management as defined by the dedicated SAP.
Transfer of transparent non-access signalling as defined in the dedicated SAP.
Request of various types of E-RABs through the dedicated SAP.
Perform the mobility function..
Traffic Security:
IP Network Security
LTE is designed with many operators both for core networks and access networks in mind. Whilst this introduces a great deal of flexibility it also introduces a number of new security issues.
The backhaul of LTE is all IP with the eNB having Ethernet interfaces. Where previously backhaul may be secured with physical protection, home eNodeBs may mean we cannot trust the transport network security.
Core network is generally a trusted zone, and secured physically.
RAN is not trusted, anyone can intercept messages over the air. The eNodeB itself must be trusted as this provides security termination.
Transport links are secured need to be secured with IPsec if required
LTE Basic provides a traffic security for radio interface based on integrity
protection and ciphering of RRC messages as well as ciphering of UP data
messages.
Integrity protection is implemented in the PDCP layer in order to ensure that
the data origin of the signaling data received is indeed the one claimed. In
addition, integrity protection allows the receiving entity (UE or eNodeB) to
verify that the received data has not been modified in an unauthorized way
since it was sent by the sending entity (UE or eNodeB).
Ciphering is implemented in the PDCP layer in order to ensure that user data
and signaling data cannot be eavesdropped on the radio access interface.
Ciphering is applied to Signaling Radio Bearers (SRB) and Data Radio
Bearers (DRB).
As security protection is performed between the eNodeB and UE whereas
NAS is performed between UE and MME.
LTE Basic Features
The O&M solution in LTE is characterized of providing SON functionality and
support and smart simplicity i.e. it is possible to utilize smart functions in the
eNodeB to simplify the management. This means that the eNodeB will be easy
to deploy and maintain.
It is possible to access the eNodeB with the eNodeB Element Manager (EM)
and the OSS-RC. Most work, except physical work on the eNodeB, is possible
to do remotely. The allowed locations for accessing the eNodeB are defined
when setting-up the security for it. O&M on network level and integration to
Network Management System (NMS) is provided in OSS-RC.
The eNodeB provides the following support for Fault Management (FM),
Configuration Management (CM), Performance Management (PM), Security
Management (SM) and Inventory Management (IM);
More about O&M Functions can be found in a Module XXX.
Lte optional features
The Main topic is included in the Learning part of the module where you present the topics to learn.
Think of this when sequencing the included topics:
Is there a logical order to present? Chronology, process, cause->consequence
Start with the simple and build to complex.
Start with the well known (or analogies) and move to the unknown.
Do not include everything you have to say. Remember that most learning content is forgotten within a couple of days.
Focus on a few key concepts where you don’t want your audience to do the wrong thing in their work. Let the details remain on the intranet, guidelines, documentation etc.
RAN Functionality Products
Clock Source over NTP
CDMA2000
Support for cascading of 3GPP Compatible RET Antennas
Support for 3GPP Compatible TMA
Support for 3GPP Compatible RET
Antennas
RAN Functionality Products are divided into LTE Basic Functions and LTE Optional Functions
Optional Functions are divided into 7 areas:
Radio Performance
Product is scalable on a number of Connected Users.
Please Note: Grey boxes are related to L10 release of the product
And green are related to L11A. This is only an overview figure.
LTE Optional:
Most LTE features are priced per connected users. The connected user
feature sets the eNodeB licensed user capacity and facilitates "pay as you
grow" pricing scheme for SW features.
SW license keys enable eNodeB capacity in terms of maximum allowed
simultaneous Connected Users. The active users are defined as connected
terminals served by the eNodeB, residing in the RRC Connected state (as
defined in 3GPP).
Through the appropriate observability for the capacity licenses, the system
helps the operator to optimize the usage of the SW licenses on a per eNodeB
basis. The maximum range for the amount of simultaneous Connected Users
orderable in L10A is 100 UEs and for L11A each eNode B can support up to 200 users.
Observability in form of counters is provided to help identify the need for
growth..
Capacity Licence
Channel Bandwidth
# Channel Bandwith
In release L11A, cells can be configured with additional channel bandwiths: 1,4 MHz and 3 MHz
Before configuring cell channel bandwidth used RU capability needs to be checked as well.
With Release L10B each Digital Unit of type DUL can handle up to three cells except for 20MHz where each DUL can handle only 1 cell.
Release L11A adds support for three cells per DUL also with 20MHz channel bandwith.
Capacity Licence
HW Related
DlBasebandCapacity (Mbps)
UlBasebandCapacity (Mbps)
# HW Related
LTE Optional:
HOM
With use of Higher Order Modulation (HOM) data rate is increased and Link Adaptation function can work in a efficient manner.
16QAM in UL
With the use of 16 QAM modulation the maximum bitrate on the uplink can be
increased. The uplink peak rates are doubled by using 16 QAM modulation compared to
QPSK modulation.
The higher modulation formats enables that more information can be
transferred in each radio symbol. This enables a higher peak rate in good radio
conditions.
64 QAM in DL
With the use of 64 QAM modulation the maximum bitrate on the downlink can
be increased by approximately 50% compared to 16 QAM modulation.
The higher modulation formats enables that more information can be
transferred in each radio frame. This enables a higher peak rate when the
channel conditions are good.
The Dual-Antenna Downlink Performance Package provides support for dual layer
transmission (spatial multiplexing) and transmission diversity modes for
dual antenna configurations.
Description
Spatial multiplexing schemes are an efficient way of increasing the bit rate
through the use of multi layer transmissions (a.k.a. MIMO or multi-stream). This
improves both peak-rate and average throughput without having to increase the
radio bandwidth which translates to an improvement of the spectral efficiency
(bits/Hz) at full traffic loads.
The dual antenna transmission will also improve the coverage, i.e. the bit rates
at cell edge.
The Dual-Antenna Downlink Performance Package supports configurations
with up to two data streams according to the 3GPP Release 8 specification.
The recommended antenna configuration to fully benefit from the Dual-Antenna
Downlink Performance Package is two antenna elements with a minimum of
correlation between the elements, e.g. two cross-polarized elements.
The feature also includes full rank adaptation for the (switching from singe to
dual layer transmission, and back) on a per user and transmission time interval
level to support bitrates improvements at all SINR levels for all UEs.
The following 3GPP transmission modes are supported:
Mode 1: Single Antenna Port
Mode 2: Transmit Diversity
LTE Optional:
LTE
WWW
The Multiple Radio Bearers per User service provides the ability for a user to
have up to 8 simultaneous data bearers established with different QoS
requirements at a given instance. This allows a user to e.g. download a large
file using FTP and use video streaming at the same time with acceptable end
user performance. The system will differentiate (based on QoS requirements)
the service data flows and establish separate , up to 8, radio bearers to a user.
This prevents a large data transfer from "blocking" a delay sensitive data
transfer, as would be the case if only single data radio bearer per user was
supported. Without this feature the LTE user experience would be lower when
running multiple service data flows with different delay requirements.
Cell ID-based location support
S!AP: Location Reporting Control
MME
CGI1
CGI2
CGI3
eNB1
CGI4
CGI5
CGI6
eNB2
Intra eNB Handover
Inter eNB Handover
S1AP : Location Report (CGI)
The feature Cell id based location support guarantees that MME will always have the correct Cell Global ID for the served active UE that can be used for location based services.
Location Report for a given UE can be triggered at Intra/Inter eNB Handover and it can be sent as an answer for the direct request from the MME!
Mobility
Mobility
GRAN
Mobility:
Evaluation
LTE
LTE
UE measures on cells and reports only when event criteria is met
- A neighbour cell becomes offset better than serving cell (A3)
- Serving cell becomes worse than an absolute threshold (A2)
Intra-LTE Handover is the basic mobility function for UEs in active mode.
When one or more neighbor cells are better than current serving cell the UE is
ordered to handover to best cell. Best cell evaluation is based on
measurements of neighbor cells, serving cell and evaluation algorithm
controlling parameters set by eNodeB.
In L10A there are two possible events:
Event A3 A neighbour cell becomes offset better than serving cell that can trigger Intra LTE Handover
Event A2: Serving cell becomes worse than an absolute threshold that can triger Coverage triggered IRAT Session Continuity
Intra lte handover
sMeasure
Event A3: Neighbour becomes amount offset better than serving
Intra LTE Handover
The user equipment uses parameters sent by the RBS to determine when to perform handover measurements. Measurements commences on the serving and neighboring cells when the RSRP of the serving cell falls below the value defined in the sMeasure parameter. The user equipment detects neighboring cells via intra-frequency searches.
The user equipment uses either RSRP or RSRQ measurements to determine whether to enter the EventA3 condition. The triggerQuantityA3 parameter is used to configure where RSRP or RSRQ values are used to trigger EventA3.
Measurements of RSRP and RSRQ are performed on the serving and detected neighboring cells. The user equipment then uses an offset value, a3offset, and a hysteresis value, hysteresisA3, to determine whether to trigger the EventA3. Non default offset relationships use the value cellIndividualOffsetEUtran instead of a3offset for the particular cell relationship.
The formula used by the user equipment for evaluating entry to EventA3 is shown in the following equation:
Equation 1 Mn – hysteresisA3 > Ms + a3offset
where:

Mn = measured value of the neighboring cell (either RSRP or RSRQ)
Ms = measured value of the serving cell (either RSRP or RSRQ)
Once EventA3 is triggered, the user equipment waits a predetermined time ( timeToTriggerA3) before it commences sending measurement reports to the serving RBS. These measurement reports contain measurements for the serving cells and up to three detected intra-frequency neighbor cells. The reportQuantityA3 parameter indicates whether RSRP or RSRQ measurements, or both, are to be included in the measurement reports.
Measurement reports are sent periodically while the EventA3 condition is active. The parameter reportIntervalA3 determines the time interval between measurement reports. The parameter reportAmountA3 indicates how many reports to send; a value of 0 indicates that the reports should be sent indefinitely while the EventA3 condition is active.
The user equipment uses the same offset and hysteresis values to determine when to leave EventA3 when the serving cell improves in RSRP or RSRQ relative to the neighboring cells. The formula used by the UE is shown in the following equation:
Equation 2 Mn – hysteresisA3 > Ms + a3offset
where:

Mn = measured value of the neighboring cell (either RSRP or RSRQ)
Ms = measured value of the serving cell (either RSRP or RSRQ)
The Measurement Reports are event-triggered and resent periodically as long as the event is fulfilled.
LTE optional
SGW/
PGW
MME
LTE
RRC
Handover signaling is performed over Uu and in case of intereNodeB
handover also over the X2 interfaces if X2 is established. If not X2 is
possible to use, e.g. between MME pool borders, an S1 based handover is
used instead.
intra lte handover
inter-connection of eNBs supplied by different manufacturers;
support of continuation between eNBs of the E-UTRAN services offered via the S1 interface;
separation of X2 interface Radio Network functionality and Transport Network functionality to facilitate introduction of future technology
System Information:
Inter-frequency mobility
redirectionInfoRefPrio1
GeranFreqGroup
UtranFrequency
Cdma2000Freq
EUtranFrequency
eNodeB
System Information Block Type 5 is the SIB that contains information about other E-UTRA frequencies and inter-frequency neighbor cells relevant for cell reselection
Mobility:
GeranFreqGroup
UtranFrequency
Cdma2000Freq
EUtranFrequency
SIB
SIB6
tReselectionUtra
tReselectionUtraSfHigh
tReselectionUtraSfMedium
In idle mode system information includes information about the WCDMA,
priority and thresholds for this RAT which is needed for efficient mobility. SIB6
is included in the system information.
In connected mode the serving cell is evaluated and in case of bad coverage a
release with redirect information is performed. The redirect information
includes the WCDMA carrier frequency, the information is preconfigured in
eNodeB. Without requiring a complex relation to WCDMA the feature improves outage
time when the UE is moving out of LTE coverage but still within WCDMA
coverage.
In idle mode system information includes information about the WCDMA,
priority and thresholds for this RAT which is needed for efficient mobility. SIB6
is included in the system information.
In connected mode the UE is ordered by the eNodeB to perform bad coverage
event evaluation on serving cell. The UE is configured to send an event
triggered measurement report if a bad coverage criterion is fulfilled. When a
measurement report is received by the e

lte l11 radio network functionalities

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